(I)记 F(x)=f(x)g(x) ,讨论函F(x)单调性;
(II)令G(x)=af(x)+g(x)(a∈R),若函数G(x)有两个零点.
(i)求参数a的取值范围;
(ii)设x1,x2是G(x)的两个零点,证明x1+x2+2<0.
—I usually share them my classmates and talk about the stories each other.
下列选项是四则“遗失启事”的主要内容,其中表达通顺、得体的一项是( )
—Has Jack finished painting the picture yet?—I've no idea. But he______ it the whole afternoon.